Concrete floor construction with duct-forming voids



I of 3 l/v VENTO/PSJ k'ermeih CJl/aslwzd 7 Sheet K. C. NASLUND ET LCONCRETE FLOOR CONSTRUCTION WITH DUCT-FORMING VOID y leonardfl, Bihlanat'ys May 6, 1969 Filed May 31,

3,442,058 CONCRETE FLOOR CONSTRUCTION WITH DUC'I'FORMING VOIDS y 1959 K.c. NASLUND ETAL Sheet Filed May 31,

I N Vf N 70/23 1761/2 CiNaslund & I'd/1. 81' [er dig/.5

1 80710 5 MZMY y 1969 K. c. NASLUND ET AL 3,442,058

CONCRETE FLOOR CONSTRUCTION WITH DUCT-FORMING VOIDS Filed May 31, 1968Sheet 3 ors Q W T /a6 ("2 I10 16 26 e4 5- 32 26-..- g o I [N Vf/V T023ksnnczlz 6'.Nasland a by Leonard A. Bz'klcr United States Patent U.S.Cl. 52- 221 32 Claims ABSTRACT OF THE DISCLOSURE A concrete floorconstruction comprising a reinforced concrete lower slab having hollowpreformed cells embedded between a monolithic structure of crisscrossingconcrete ribs, said cells being made of concr te, gypsum, vitrified clayor the like, said lower slab having ducts extending between said cellsand embedded in said ribs for handling the flow of air, a plurality ofpreformed blocks or the like covering the upper side of said lower slab,each of said blocks having an upper horizontal rim portion with at leastone inverted generally frusto-conical member projecting downwardlytherefrom and having a flat horizontal bottom surface engaging the lowerslab, each member being hollow and having a central opening thereinextending downwardly to the lower slab, said blocks being made ofconcrete, gypsum, vitrified clay or the like, and an elevated concreteslab extending over and covering said preformed blocks, said elevatedslab extending downwardly through said openings in said frusto-conicalmembers and forming 'bonds with the lower slab, said preformed blocksforming air passages between and around said frusto-conical members.

This application is a continuation-in-part of our copending applicationSer. No. 514,948, filed Dec. 20, 1965, and now abandoned.

This invention relates to the construction of reinforced concrete floorsfor buildings and other structures.

One object of the present invention is to provide a new and improvedreinforced concrete floor construction which embodies ducts or passagesfor supplying or returning air in connection with the heating andcooling of the building or other structure.

A further and more specific object is to provide a concrete floorconstruction comprising a reinforced concrete lower slab. A plurality ofpreformed blocks are placed on the upper side of the lower slab, so asto cover the lower slab. Each block comprises at least one inverted,generally frusto-conical member engaging the lower slab. Eachfrusto-conical member is hollow and is formed with a central openingextending downwardly to the lower slab. Moreover, each frusto-conicalmember has a flat horizontal bottom surface which engages the lowerslab. Each preformed block also has an upper horizontal rim portion ofrectangular shape, such rim portion being aligned with the rim portionsof the adjacent blocks. An elevated concrete slab is poured over thepreformed blocks so as to cover the blocks. The elevated slab extendsdownwardly through the openings in the frusto-conical members so as toform bonds with the lower slab. The preformed blocks provide spacesbetween and around the frusto-conical members, and are effective toexclude the concrete of the elevated slab from such spaces, whereby thespaces provide passages for air or the like.

Another aspect of the present invention relates to the preformedbuilding block as such, comprising a preformed member having a generallyhorizontal upper flange portion and a downwardly tapering hollowportion. The hollow portion is formed with a generally axial openingextending in a generally vertical direction. Moreover, the hollowportion has a flat horizontal bottom supporting surface, whereby theblock may be supported on a concrete slab or the like.

The building block may have one or more of the downwardly taperinghollow portions projecting downwardly from the upper flange portion.

In another aspect, the present invention comprises a concrete floorconstruction, including a concrete slab having a plurality of hollow,generally rectangular, preformed cells embedded therein and spaced apartin the slab. A monolithic structure of crisscrossing ribs of concrete ispoured between the cells. Each cell comprises upper and lower half-boxeswith open ends facing each other and forming a chamber in the cell. Eachhalf-box has a closed end wall, directed upwardly or downwardly, and aplurality of side walls projecting toward the open end of the half-box.At least some of the side walls of the half-boxes are formed withnotches at the open ends of the half-boxes. Duct members are closelyreceived in the notches so as to extend 'between the chambers in theadjacent cells, to handle a flow of air between the chambers. The ductmembers are embedded in the concrete ribs between the cells. This floorconstruction may be employed by itself, or as the lower slab in thepreviously described composite floor construction, in which the lowerslab supports the preformed blocks and the elevated slab. In thecomposite floor construction, two sets of air ducts are provided in theupper and lower slabs. Thus one set of ducts may be employed forsupplying air, while the other set of ducts is employed for returningthe air to the central heating or air conditioning plant.

Further objects and advantages of the present invention will appear fromthe following description, taken with the accompanying drawings, inwhich:

FIG. 1 is a fragmentary elevational section showing a composite floorconstruction to be described as an illustrative embodiment of thepresent invention.

FIG. 2 is a fragmentary elevational section similar to FIG. 1 andshowing additional features of the floor construction.

FIG. 3 is a fragmentary diagrammatic plan view of the floor constructionof FIG. 1.

FIG. 4 is an elevational view, partly in section, of one of the upperpreformed blocks for the floor construction.

FIG. 5 is a plan view of the preformed block shown in FIG. 4.

FIG. 6 is a fragmentary enlarged section showing details of a jointbetween two of the upper preformed blocks.

FIG. 7 is a fragmentary sectional perspective similar to FIG. 6 butshowing a modified joint construction.

FIG. 8 is a fragmentary elevational section showing the jointconstruction of FIG. 6 as incorporated into the finished floor.

FIG. 9 is a fragmentary elevational section showing a modified airterminal unit for use with the floor construction.

FIG. 10 is a fragmentary elevational section showing a baseboard type ofair outlet for use with the floor construction.

As already indicated, FIG. 1 illustrates a reinforced concrete floorconstruction 20 which incorporates complete structural, mechanical andelectrical facilities. The floor 20 is incorporated into a building orother structure 22 having columns 24 and walls 26 for supporting theconcrete floor.

It will be seen that the concrete floor 20 comprises a poured concreteslab 28 with reinforcing rods, cables 3 or other members 30 embeddedtherein. The reinforcing members 30 are normally made of steel, butother materials of high tensile strength may be employed.

A plurality of hollow preformed cells 32 are incorporated into theconcrete slab 28 to reduce the weight of the slab, while also providingducts or conduits for carrying air, as well as openings or spaces forelectrical and other facilities. The illustrated cells 32 are square, asviewed from the top, but they may be rectangular or some other suitableshape. The cells 32 preferably extend through the slab 28 for the fulldepth thereof, but the depth of the slab may exceed the height of thecells, in which case the slab will completely cover the cells.

As shown in FIG. 3, the cells 32 are preferably arranged in a regularrectangular pattern, so that the poured concrete slab 28 will haveintersecting ribs 34 extending between the cells. The ribs 34 arearranged in a pattern resembling a rectangular grid as viewed from thetop. It will be seen that certain of the reinforcing rods or othermembers 30 are appropriately placed in the ribs 34 so that therectangular grid formed by the ribs is capable of providing the mainstructural support for the floor. The grid-like ribs 34 act as beams tosupport the weight of the floor as well as the load which is placed onthe floor, due to use of the building.

Preferably, each of the rectangular cells 32 comprises a pair ofpreformed blocks or shells 36 which are stacked, one upon the other,during the construction of the floor. Each of the illustrated blocks 36is in the form of a rectangular tray or half-box, comprising ahorizontal wall 38 and a set of four side walls 40. The block is open onthe side opposite from the horizontal wall 38. The blocks 36 arepreferably made of precast concrete, but may also be made of gypsum,vitrified clay, or other suitable materials.

The blocks 36 are assembled with the lower block in an upright position,to open upwardly, and with the upper block in an inverted position, toopen downwardly into the lower block. Thus, the horizontal wall 38 ofthe lower block forms the bottom wall of the cell 32. The horizontalwall 38 of the upper block forms the top wall of the cell. The sidewalls 40 of the superimposed blocks are aligned with one another to formthe side walls of the cell 32.

In the construction of the concrete slab 28, temporary forms are builtto support the slab. The pairs of blocks or half-boxes 36 are placed onthe forms in the desired rectangular pattern. The reinforcing members 30are placed above the forms. Then, concrete is poured into the forms to adepth corresponding to the total depth of the stacked blocks 36. Theconcrete fills the spaces between the cells 32 so as to form the ribs34. After the concrete has hardened and cured sufficiently, thetemporary forms may be removed. It will be evident that the fillerblocks 36 serve as permanent forms which are incorporated into thepoured concrete slab 28 to form the cells 32.

In order that the hollow cells 32 may serve as air ducts,interconnecting conduits or ducts 42 are provided between the cells. Theconduits 42 may be made of sheet metal or other suitable materials. Inthe illustrated construction, openings 44 are formed in the side walls40 of the blocks 36 to receive the conduits 42. The illustrated openings44 are oval in shape but may be of any suitable shape. One half of eachof the openings 44 is formed in each of the superimposed blocks 36. Theopenings are preferably preformed in all four sides of the blocks 36.Any of the openings which are not needed or desired may be closed bysuitable panels 46 during the construction of the concrete slab 28. Thepanels 46 may be made of sheet metal or other suitable material.

The conduits or pipes 42 are installed between the blocks 36 as theblocks are positioned on the temporary forms during the construction ofthe floor. Thus, all of the conduits 42 are in place before the concreteis poured to complete the slab 28. As shown in FIG. 1, some of the cells32 may be formed with air openings 48 for admitting or discharging air.Each opening 48 is preferably formed in the lower horizontal wall 38 ofthe corresponding cell 32. A grill or louver structure 50 may be mountedin or over the opening 48. The opening 48 may be preformed in thecorresponding block 36, or may be cut through the horizontal wall of theblock.

The hollow cells 32 may also be employed to carry other facilities suchas pipes 52 for an automatic sprinkler system. As shown in FIG. 1, thepipes 52 extend through the conduits or ducts 42. Sprinkler heads 54 maybe connected to the pipes 52 by means of suitable branch pipes 56.Openings 58 may be drilled or otherwise formed in the lower horizontalwalls 38 of the cells 32 to accommodate the sprinkler heads 54.

The lower slab 28 may be employed by itself, in some cases, but it ispreferred to employ the slab 28 to support an elevated floor structure60 which incorporates other mechanical and electrical facilities. Asshown in FIG. 1, the elevated floor structure 60 employs preformedblocks 62 which provide hollow spaces or passages 64 within the elevatedfloor structure. The passages 64 are preferably employed as ducts orconduits to carry air in connection with the heating or cooling of thebuilding. Thus, the concrete floor 20 provides two sets of air passages.One set is formed by the lower cells 32 and the interconnecting ducts42, while the other set is formed by the passages 64 in the elevatedfloor structure 60. It is preferred to employ the upper passages 64 tosupply air to the rooms of the building, while the lower passages in thecells 32 are employed for the return flow of air. However, thissituation could be reversed. During the heating season, warm air ispreferably supplied through the upper passages 64 so that the upperfloor structure 60 will be heated to provide a radiant heat transfercomponent for the rooms of the building. The heated air may also bedischarged into the rooms of the building. Cool air may be suppliedsimilarly. The preformed blocks 62 are preferably made of precastconcrete, but may be made of other suitable materials, such as gypsum,vitrified clay, or the like.

As shown to particular advantage in FIGS. 4 and 5, the illustratedpreformed blocks 62 comprise members 66 which are generallyfrusto-conical in shape but are inverted so that the passages 64 will beformed between the adjacent members. The illustrated frusto-conicalmembers 60 are curved or arching rather than being straight in slope.Each member 66 is hollow and thus is generally in the form of anupwardly flaring tube, resembling the bell of a trumpet or flower of amorning glory. The lower end of each member 60' is circular, but theupper end forms a square or rectangular rim 68.

Each of the illustrated preformed blocks 62 is formed with two of thefrusto-conical trumpet-shaped members 66. However, this situation couldbe varied. Thus, for example, it would be convenient in some cases toform each frusto-conical member 66 as a separate block, or to combinefour of the members 66 into a single block.

The upper floor structure 60 is constructed after the lower concreteslab 28 is completed. The preformed fillers or blocks 62 are placed onthe slab 28 in the desired pattern. In the illustrated construction,four of the inverted frusto-conical members 66 are placed over each ofthe cells 32 in the slab 28. Thus, two of the blocks 62 are placed overeach cell 32, as will be evident from FIG. 3. The size of the blocks 62corresponds to the size of the cells 32 plus the width of the concreteribs 34 between the cells.

The rectangular rims 68 of the upper form blocks 62 are made to providecontinuous coverage of the slab 28, except for the upwardly flaringopenings 70 in the frusto-conical members 66. Such openings 70 extendall the way through the blocks 62. After the upper form blocks 62 are inplace, concrete is poured over the blocks to form a continuous deck orfloor surface 72. The concrete fills the openings 70 within thefrusto-conical members 66 and comes into contact with the upper side ofthe lower slab 28 within each of the openings. Thus, bonds are formedbetween the upper slab or deck 72 and the lower slab 28 within theopenings 70 in the blocks 62. In this way, the slabs 28 and 72 aresecurely joined to form a unitary structure.

Before the upper concrete slab 72 is poured, electrical conduits orraceways 74 and 76 may be mounted over the blocks 62. The conduit 74 maybe used for power wires, while the conduit 76 may be employed fortelephone or other signal wires. As shown, the conduits 74 and 76 arepreferably located over the frusto-conical members 66. In this way,cross-overs between the conduits may be formed by providing offset orbent portions 78 which dip downwardly into the openings 70 within thefrusto-conical members 66.

Provision should be made for all mechanical and electrical facilities,insofar as possible, before the upper concrete slab 72 is poured. Thus,branch conduits 80 may be extended downwardly from the power conduit 76through the openings 70 in the frusto-conical members '66 to affordelectrical connections for lighting fixtures 82 or other electricalunits to be mounted on the underside of the lower slab 28. A suitableopening 8-4 may be drilled or otherwise formed through the upperhorizontal wall 38 of the corresponding cell -32 to accommodate thebranch conduit 80. A flexible conduit 86 is preferably employed betweenthe lower end of the branch conduit 80 and the lighting fixture '82. Anopening 88 may be drilled or otherwise formed in the lower horizontalwall 38 to accommodate the flexible conduit 86.

It will be evident that the opening 70 in the frustoconical members 66of the upper form blocks 62 provide convenient access to the cells 32 ofthe lower slab 28. Holes may easily be drilled through the upper walls38 of the cells to accommodate electrical conduits and other facilities,as needed.

The upper slab 72 provides a smoothly finished, continuous floor surface90. If desired, acoustical plaster or other suitable finishing material92 may be applied to the underside of the slab 28 to provide anattractive ceiling surface for the rooms below.

It is preferred to supply air to the passages 64 in the elevated floorstructure 60 from a central source, such as a blower or fan. The airsupplied to the passages 64 is normally heated during the heating seasonand cooled when air-conditioning is required. During the heating season,the heated air warms the upper slab 72 so that it provides a componentof radiant heat transfer.

Various outlet or terminal devices may be employed for discharging theair from the passages 64 into the rooms of the building. One suchterminal device 94 is illustrated in FIG. 1. The terminal device 94 ismounted above the upper slab 72 and adjacent one of the Walls 26. Anopening 96 is formed in the edge portion of the upper slab 72 to providefor the flow of air from the passages 64 to the terminal device 94. Itwill be seen that the terminal device 94 comprises a housing 98 havingopenings 100 therein for discharging the air into the room. The airpasses upwardly from the opening 96 and through an induction nozzle 102.into the housing 98, and then out of the housing through the openings100. A regulating or balancing damper 104 may be provided in the housing98 below the nozzle 102.

The terminal device 94 also includes a unit 106 for drawing air into thehousing 98 from the room through openings 108. Such air is dischargedfrom the housing 98 through the openings 100. The unit 106 is capable ofheating or cooling the air drawn from the room. For this purpose, theunit 106 is connected to pipes 110 and 112 through which a heating orcooling fluid may be supplied to the unit 106. Thus, for example, hotwater may be supplied to the unit .106 during the heating season, whilechilled water may be supplied during the cooling season.

As already indicated, air is returned from the rooms to the interior ofthe cells 32 through the return air grills or louvers 50. The return airis preferably carried to the central fan or blown by the cells 32 andthe interconnecting ducts 42.

Air may also be returned to the cells 32 through openings 114 in thelighting fixtures 82. The air passes upwardly into the overlying cellsthrough openings 116 which are drilled or otherwise formed in the lowerwalls 38. The air passing through the lighting fixtures 82 is heated toan appreciable extent by the heat of the lamps 118. This heat passesinto the cells 32 and thus is recovered by the central ventilatingsystem.

Additional features of the floor construction are shown in FIG. 2. Itwill be understood that the various features are optional and may beemployed as needed.

While the lighting fixture 82 of FIG. 1 is of the fluorescent type, FIG.2 illustrates an incandescent type lighting fixture 120 which isrecessed upwardly into one of the cells 32. An opening 122 is formed inthe lower Wall 38 of the cell 32 to accommodate the lighting fixture120. A flexible electrical conduit 124 is preferably employed to supplypower to the fixture 120. Like the flexible conduit 86 of FIG. 1, theflexible conduit 124 is connected to one of the branch conduits 80 whichcomes down through the opening in one of the frusto-conical members 64.It will be seen that the flexible electrical conduit 124 extends throughone of the interconnecting ducts 42 between the cells 32. The ducts 42make it easy to install electrical fixtures or appliances in any of thecells 32, even after the entire floor has been completed. The fixturemay simply be connected to the nearest branch conduit through the ducts42.

The lighting fixture 20 may also function as a return air inlet. Thus,air may enter the fixture through the lower opening 126 therein, and maypass out of the fixture into the cell 32 through louvered openings 128in th sides of the fixture.

Various terminal devices may be employed to supply air from the passages64 in the elevated floor 60 to the rooms below the lower floor slab 28.FIG. 2 illustrates such a terminal unit 130, which is in the form of ahollow tubular housing extending through the entire thickness of thelower slab 28 from one of the passages 64. If desired, a variable volumedamper 132 may be installed in the terminal device 130, to provide forthe regulation of the amount of air supplied to the room below.

A suitable opening 134 is cut or otherwise formed in the lower wall 38of the cell 32 to accommodate the upper end of the terminal unit 130.The opening 136 may be drilled or cut from below by working through theopening 134. Thus, additional terminal units may easily be installedafter the entire floor has been completed.

FIG. 2 also illustrates another terminal unit 138 which is the same asthe terminal unit 130, except that a heating device 140 is installed inthe terminal unit 138, instead of the blower 132. The heating unit 140is illustrated as being an electric heater. A flexible electricalconduit 142 is connected between the heater 140 and one of the branchconduits 80. The electric heater 140 may be thermostatically controlledto provide individual regulation of the temperature in the room below.

As illustrated in FIG. 3, the cells 32 may be made smaller in thevicinity of the column 24. Moreover, the cells 32 may be spaced apartmore widely in the neighborhood of the columns 24. In this way, theamount of poured concrete is increased in the vicinity of the columns24, so as to increase the strength of the lower slab 28. In this way,the slab is adequately strong to resist the greater shear stresses whichexist around the column.

When the elevated floor structure 60 is being constructed, the preformedblocks 62 may be stabilized by employing devices therebetween formaintaining alignment between the adjacent blocks. FIG. 6 illustratessuch an aligning device 144, which comprises a pair of plates 7 orwashers 146 adapted to form bridges between the rim portions 68 of theadjacent blocks 62. The washers 146 engage the upper and lower sides ofthe rim portions 68. A bolt 148 is preferably employed to clamp thewashers 146 against the rim portions 68. The bolt 148 extends throughthe washers 146 and through the joint between the adjacent rim portions68. Notches 150 may be formed in the rim portions 68 to accommodate thebolt 148. A wing nut 152 is preferably provided on the bolt 148 so thatit may readily be tightened against the washers 146.

FIG. 7 illustrates another aligning device 154 which may be substitutedfor the device of FIG. 6. The aligning device 154 is in the form of aclip which is H-shaped in cross section. Thus, the device 154 has upperand lower flanges 156 with a central web 158 extending therebetween. Theflanges or plates 156 engage the upper and lower sides of the adjacentrim portions 68, while the Web 158 passes between the adjacent rimportions. The clip 154 may also be described as being I-shaped in crosssection.

FIG. 9 illustrates a terminal device 160 which is similar to theterminal device 94 of FIG. 1, except that the terminal device 160 isadapted particularly for use in sChOOl buildings. Thus, the terminaldevice 160 employs a housing 162 which extends to a greater height thanthe housing 98, so that book shelves 164 may be built into the lowerportion of the housing 162. The other components of the terminal device160 are the same as illustrated in FIG. 1 and are given the samereference characters.

FIG. 10 illustrates a baseboard-type of terminal device 166, in the formof a low housing adapted to extend along one wall of the building inplace of the baseboard. An opening 168 is formed in the upper slab 72 sothat air may pass upwardly through the passages 64 into the terminaldevice 166. The air passes out of the terminal device 166 through one ormore openings 170 therein. Heating or cooling coils may be provided inthe housing 166, if desired.

It may be helpful to review the procedure which is employed inconstructing the floor of FIG. 1. Temporary forms are erected to supportthe cells 32, which are placed upon the forms in a regular rectangularpattern. Each cell 32 comprises two of the preformed, pan-shaped blocksor half-boxes 36, stacked edge to edge. The reinforcing rods or membersare also mounted over the temporary forms. The interconnecting ducts orconduits 42 are installed between the adjacent cells 32. Any unusedopenings 44 in the cells are closed by the panels 46. The sprinklerpiping 52 and any similar facilities are installed in the ducts 42.

After these preparations have been made, the concrete is poured into theforms to form the slab 28, including the ribs 34 between the cells 32.The ribs 34 form a rectangular grid which provides the main structuralsupport for the floor. The concrete is illustrated as being poured to adepth corresponding to the height of the cells 32, so that the pouredconcrete will be flush with the upper sides of the cells. However, theslab may be poured to a greater depth so as to cover the upper sides ofthe cells.

After the concrete in the slab 28 has hardened, the upper preformedblocks 62 are placed on the slab. Two of the blocks 62 are located overeach cell 32. Inasmuch as each block 62 comprises two of thefrusto-conical members 66, there are four of the frusto-conical membersover each cell 32. The blocks 62 provide continuous coverage for theslab 28, except for the central openings in the frusto-conical members66.

The stabilizing devices 144 may be installed between the adjacent formblocks 62, as shown in FIGS. 4, 6 and 8. Alternatively, the stabilizingor aligning devices 154 of FIG. 7 may be employed.

The electrical conduits or raceways 74 and 76 are mounted over thepreformed blocks 62. Crossovers may be provided between the conduits byproviding the downwardly bent portions 78 which dip into the openings inthe frusto-conical members 66.

The branch electrical conduits 80 are extended downwardly from theconduits 74 through the openings 70 in the preformed blocks 62. Thenecessary openings 84 are drilled or otherwise formed in the upper walls38 of the cells.

After all the desired electrical and other faciliti s are in place,concrete is poured over the preformed blocks 62 to form the upper slab72. The concrete fills the openings 70 in the blocks 62 and forms bondswith the upper side of the lower slab 28.

After the floor has been completed, openings may be cut or otherwiseformed in the lower wall 38 of the cells 32 to accommodate the lightingfixtures 82 and 120, the return air grills 50, the terminal units and138, and any other fixtures or facilities which may be desired.

The passages 64 formed by the frusto-conical members 66 of the upperblocks 62 are preferably employed to carry air to be supplied to therooms of the building. The air supplied to the passages 64 is heatedduring the heating season. In this way, the floor is heated so that itprovides radiant heating. The air is discharged into the rooms by thevarious types of terminal units 94 (FIG. 1), 130 and 138 (FIG. 2), (FIG.9), and 166 (FIG. 10). Inasmuch as the passages 64 extend throughout theentire elevated floor structure 60, a terminal unit may be located atany desired point above the floor, at either an exterior or an interiorlocation. When remodelling is necessary, an opening may easily be cutthrough the upper slab 72 into one of the passages 64.

If it is desired to supply air to the room below, a terminal unit may beinstalled so as to extend through any of the cells 32. Such terminalunits are illustrated in FIG. 2.

The preformed blocks 62 of the elevated floor structure 60 arepositioned so that four of the frusto-conical members 66 are located ina regular pattern over each of the cells 32 in the lower slab. Thus, oneof the passages 64 in the elevated floor structure 60 is disposeddirectly over the center of each cell 32. This arrangement is highlyadvantageous, because one of the terminal devices, of the typeillustrated in FIG. 2, may be installed in any cell, with completeassurance that the upper end of the terminal device will have fullcommunication with the passages 64 in the elevated floor structure.

Return air openings may be provided as needed in the lower walls of thecells. The lighting fixtures may also be constructed so as to serve asreturn air openings.

The passages 64 in the elevated floor structure 60 may be divided intozones or sections, if desired, by inserting panels between the preformedblocks 62 during the construction of the floor. In this way, thetemperature or volume of the air supplied to the various zones may becontrolled separately.

Similarly, the closure panels 46, as shown in FIG. 1, may be employed todivide the lower slab 28 into zones or sections, so that the flow of airin the various zones may be controlled separately. The panels 46 areadapted to close the openings 44 in the side walls 40 of the cells, asdesired.

The floor construction has the advantage of extremely low transmissionof sound, due to the provision of the upper and lower superimposedslabs, each of which comprises preformed blocks plus a large mass ofpoured concrete. Moreover, the fire rating of the floor constructron ishigh, with no need for additional fireproofing.

The concrete floor construction of the present inventron is applicableto all types of building construction. llowever, it is particularlyadvantageous for office buildings, other commercial buildings, schoolsand apartment buildings.

The upper and lower floor slabs are preferably used together, to form acomposite floor structure, but they may be used separately, or inconnection with other floor slab constructions.

The concrete fioor construction of the present inventron is not subjectto corrosion or deterioration due to high humidity, salt air, and otherfactors which normally result in the rapid corrosion of ordinary steelducts employed in conventional heating and ventilating systems. Thus,the concrete floor construction is particularly advantageous for use inthe tropics, near seacoasts, and in other areas where corrosiveatmospheric conditions are prevalent.

The supply and return air passages in the upper and lower slabs arelarge in effective cross section so that they afford ample carryingcapacity for the flow of air. Thus, the power requirement forcirculating the air is minimized. Accordingly, the cost of operating thecirculating fans is low. Moreover, the air moves at low velocity so thata minimum of noise is produced by the ventilating system.

The floor construction of the present invention is particularlyadvantageous for the construction. of buildings in cold weather, becausethe passages in the floor may be employed immediately as heating ductsto provide temporary heat in the building. There is no need to wait forthe installation of separate heating ducts.

It will be evident that the floor construction of the present inventionprovides all of the necessary structural, mechanical and electricalfacilities which will be needed in the building. Such facilities areprovided at extremely low cost, and in a manner which greatlyfacilitates the construction of the floor.

We claim:

1. A concrete floor construction, comprising the combination of areinforced concrete lower slab,

a plurality of preformed blocks covering the upper side of said lowerslab,

each of said blocks comprising at least one inverted generallyfrusto-conical member engaging the upper side of said slab,

each of said frusto-conical members being hollow and having a centralopening therein extending downwardly to the upper side of said slab,

each of said frusto-conical members having a flat horizontal bottomsurface engaging said slab for supporting the corresponding block,

each of said preformed blocks having an upper horizontal rim portion ofrectangular shape,

said rim portion being aligned edge-to-edge with the rim portions of theadjacent preformed blocks,

and an elevated concrete slab extending over and covering said preformedblocks,

said elevated slab extending downwardly through said openings in saidfrusto-conical members and forming bonds with said lower slab,

said preformed blocks having spaces between and around saidfrusto-conical members and being effective to exclude the elevatedconcrete slab from said spaces whereby said spaces provide passages forair or the like.

2. A concrete floor construction according to claim 1,

in which each of said preformed blocks comprises only one of saidfrusto-conical members.

3. A concrete floor construction according to claim 1,

in which each of said preformed blocks comprises a pair of said invertedfrusto-conical members.

4. A concrete floor construction according to claim 1,

in which electrical conduits are embedded in said upper elevatedconcrete slab above said preformed blocks, and in which at least two ofsaid conduits cross each other,

one of such crossing conduits having a downwardly olfset portion whichdips downwardly into one of said openings in said invertedfrusto-conical members at the cross-over point with the other crossingconduit.

5. A concrete floor construction according to claim 1,

comprising a terminal device disposed above said elevated concrete slaband having an outlet opening for discharging air or the like,

said elevated slab having a connecting opening extending upwardlytherein from said passages in said elevated slab for connecting saidpassages to said terminal device.

6. A concrete floor construction according to claim 1,

including a plurality of aligning devices connected between the rimportions of the adjacent preformed blocks for aligning and stabilizingsaid blocks.

7. A concrete floor construction according to claim 1,

in which a plurality of aligning devices are connected between said rimportions of the adjacent preformed blocks for maintaining said rimportions in alignment,

each of said aligning devices comprising upper and lower washersengaging the upper and lower sides of, said rim portions,

and a bolt extending through said washers and be tween said rim portionsfor clamping said washers against said rim portions.

8. A concrete floor construction according to claim 1,

in which said lower slab comprises a plurality of hollow preformed cellsembedded therein,

said cells being spaced apart in said lower slab with concretesupporting ribs disposed between said cells,

each of said cells having an upper wall flush with the upper side ofsaid lower slab,

said bottom surfaces of said inverted frusto-conical members beingsupported directly on said upper walls of said cells,

said bonds with said elevated slab being formed with said upper walls ofsaid cells.

9. A concrete floor construction according to claim 8,

comprising a main electrical conduit embedded in said elevated slababove said preformed blocks,

a branch electrical conduit connected to said main conduit .andextending downwardly through one of said openings in said invertedfrusto-conical members and through said upper wall of one of said cellsinto the corresponding cell,

and an electrical device mounted on said cell and connected to saidbranch electrical conduit,

said upper wall of said cell being formed with an opening to accommodatesaid branch electrical conduit.

10. A concrete floor construction according to claim 8,

comprising a terminal conduit extending through said lower slab from oneof said passages in said elevvated slab,

said terminal conduit extending through one of said cells,

said upper wall of the corresponding cell being formed with an openingto accommodate said terminal conduit.

11. A concrete floor construction according to claim 10,

in which said cell has a lower wall formed with another opening toaccommodate the lower portion of said terminal conduit.

12. A concrete floor construction according to claim 8,

in which a plurality of ducts are connected between the adjacent cellsand are embedded in said lower slab for the passage of air or the likethrough said cells.

13. A concrete floor construction according to claim 12,

in which at least one of said cells is formed with a bottom wall havingan opening extending therethrough for the passage of air or the like.

14. A concrete floor construction according to claim 8,

in which four of said inverted frusto-conical members of said preformedblocks are positioned over each of said cells in said lower slab.

15. A concrete floor construction according to claim 1,

in which said concrete lower slab comprises a plurality of hollowgenerally rectangular preformed cells embedded in said lower slab,

said cells being spaced apart in said? lower slab,

said lower slab comprising a monolithric structure of crisscrossing ribsof concrete disposed between said cells,

each of said cells comprising upper and lower halfboxes with open endsfacing each other and forming a chamber in said cells, each of saidhalf-boxes having a closed end wall and a plurality of side wallsprojecting therefrom toward the open end of said half-boxes, at leastsome of said side walls of said half-boxes being formed with notches atthe open ends of said halfboxes, and duct members closely received insaid notches and extending between said chambers in adjacent cells tohandle a flow of air between said chambers, said duct members beingembedded in said concrete ribs between said cells. 16. A concrete floorconstruction according to claim 1, in which said preformed blocks aremade of precast concrete. 17. A concrete floor construction according toclaim 1, in which said preformed blocks are made of gypsum. 18. Abuilding block, comprising a preformed member having a generallyhorizontal upper flange portion and a downwardly tapering hollow portionprojecting downwardly therefrom, said hollow portion having a generallyaxial opening extending therethrough generally in a vertical direction,said hollow portion having a lower end portion with a flat horizontalbottom supporting surface thereon. 19. A building block according toclaim 18, in which said hollow portion is generally of an invertedfrusto-conical shape. 20. A building block according to claim 18, inwhich said outwardly projecting generally horizontal flange portion isof substantially rectangular shape. 21. A building block according toclaim 18, in which said hollow portion is of an inverted frustoconicalshape, and in which said outwardly projecting generally horizontalflange portion is of generally rectangular shape. 22. A building blockaccording to claim 18, made of precast concrete.

23. A building block according to claim 18, made of gypsum.

24. A building block according to claim 18, made of vitrified clay.

25. A building block, comprising a preformed member having a generallyhorizontal upper flange portion with a pair of downwardly taperingportions projecting downwardly therefrom, each of said downwardlytapering portions being hollow and having an axial opening extendingtherethrough generally in a vertical direction, each of said downwardlytapering portions having a flat horizontal bottom supporting surfacethereon. 26. A block according to claim 25,

in which each of said downwardly tapering portions is of a generallyinverted frusto-conical shape.

27. A block according to claim 25,

in which said flange portion is generally rectangular in shape.

28. A concrete floor construction,

comprising a concrete slab having a plurality of hollow generallyrectangular preformed cells embedded therein,

said cells being spaced apart in said slab,

said slab comprising a monolithic structure of crisscrossing ribs ofconcrete disposed between said cells,

each of said cells comprising upper and lower halfboxes with open endsfacing each other and forming a chamber in said cell,

each of said half-boxes having a closed end wall and a plurality of sidewalls projecting therefrom toward the open end of said half-box,

at least some of said side walls of said half-boxes being formed withnotches at the open ends of said half-boxes,

and duct members closely received in said notches and extending betweensaid chambers in the adjacent cells to handle a flow of air between saidchambers,

said duct members being embedded in said concrete ribs between saidcells.

29. A concrete floor construction according to claim 28,

in which said duct members are oval in cross section,

and said notches are of corresponding semioval shape.

30. A concrete floor construction according to claim 28,

in which said cells are made of precast concrete.

31. A concrete floor construction according to claim 28,

in which said cells are made of gypsum.

32. A concrete floor construction according to claim 28,

in which said cells are made of vitrified clay.

References Cited UNITED STATES PATENTS 1,995,393 3/1935 Manske 523442,089,893 8/1937 Greulich 52-221 2,107,523 2/1938 Coe 52-380 2,294,5549/1942 Henderson 52-221 2,729,429 1/ 1956 Goemann 49 2,741,117 4/1956Hoseason 52-221 2,811,850 11/1957 Clary 52--220 FOREIGN PATENTS 26,6641954 Finland.

1,245,853 1960 France.

996,805 6/ 1965 Great Britain.

FRANK L. ABBOTT, Primary Examiner.

PRICE C. FAW, IR., Assistant Examiner.

US. Cl. X.R.

